Method of producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons, and installation for implementing same

Abstract

A method and an installation for producing a concentrate of aromatic hydrocarbons from light aliphatic hydrocarbons and from mixtures thereof with oxygenates. Initial raw material is fed into two in-series-connected reaction units, with zeolite catalysts a mixture obtained following the reaction units is separated into a liquid fraction and a gas fraction, and the gas fraction is fed to the inlet of the first and second reaction unit. The method is characterized in that the gas fraction obtained following the reaction units is separated into a hydrogen-containing gas and into a broad fraction of light hydrocarbons, containing olefins, and in that the hydrogen-containing gas is fed into an oxygenate synthesis unit, in that the resultant oxygenates are fed to the inlet of the first and second reaction unit, and in that the broad fraction of light hydrocarbons, containing olefins, is fed to the inlet of the first reaction unit.

The invention claimed is: 
     
       1. An installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons, the installation comprising:
 a serially connected first reactor and second reactor; 
 a pentasil-based zeolite catalyst; 
 the reactors configured whereby each reactor has different conditions of conversion of hydrocarbons to aromatics; 
 a separation unit connected to receive an output mixture from the second reactor, whereby the separation unit separates the output mixture into a liquid fraction and gaseous fraction, and wherein the separation unit comprises a liquid fraction output and a gaseous fraction output; 
 a line connecting the gaseous fraction output to the first and second reactors; 
 the separation unit comprising a module for separating the gaseous fraction into hydrogen-containing gas and the natural gas liquids containing olefins, and wherein the separation unit comprises a hydrogen-containing gas output; 
 a line connecting the hydrogen-containing output to an oxygenate synthesis unit to the first reactor, the second reactor or both the first and the second reactors; 
 wherein the catalyst in the first reactor comprises a mechanical mixture of two zeolites, the first of which is characterized by a silicate modulus SiO 2 /Al 2 O 3 =20 and is pretreated with an aqueous alkali solution and modified by rare-earth oxides in quantities of 0.5-2.0% by wt. of the weight of the first zeolite, while the second is characterized by a silicate modulus SiO 2 /Al 2 O 3 =82, contains residual quantities of sodium oxide 0.04% by wt. of the weight of the second zeolite, and is modified by magnesium oxide in a quantity of 0.5-5.0% by wt. of the weight of the second zeolite, where the zeolites are used in a mass ratio of 1.7/1 to 2.8/1, and the binder contains at least silica and is used in a quantity of 20-25% by wt. of the weight of the catalyst. 
 
     
     
       2. An installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons, the installation comprising:
 a serially connected first reactor and second reactor; 
 a pentasil-based zeolite catalyst; 
 the reactors configured whereby each reactor has different conditions of conversion of hydrocarbons to aromatics; 
 a separation unit connected to receive an output mixture from the second reactor, whereby the separation unit separates the output mixture into a liquid fraction and gaseous fraction, and wherein the separation unit comprises a liquid fraction output and a gaseous fraction output; 
 a line connecting the gaseous fraction output to the first and second reactors; 
 the separation unit comprising a module for separating the gaseous fraction into hydrogen-containing gas and the natural gas liquids containing olefins, and wherein the separation unit comprises a hydrogen-containing gas output; 
 a line connecting the hydrogen-containing output to an oxygenate synthesis unit to the first reactor, the second reactor or both the first and the second reactors; wherein the catalyst in the second reactor comprises a mechanical mixture of two zeolites, the first of which is characterized by a silicate modulus SiO 2 /Al 2 O 3 =20 and is pretreated with an aqueous alkali solution and modified by rare-earth oxides in quantities of 0.5-2.0% by wt. of the weight of the first zeolite, while the second is characterized by a silicate modulus SiO 2 /Al 2 O 3 =82, contains residual quantities of sodium oxide 0.04% by wt. of the weight of the second zeolite, and is modified by magnesium oxide in a quantity of 0.5-5.0% by wt. of the weight of the second zeolite, where the zeolites are used in a mass ratio of 1.7/1 to 2.8/1, and the binder contains at least silica and is used in a quantity of 20-25% by wt. of the weight of the catalyst. 
 
     
     
       3. An installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons, the installation comprising:
 a serially connected first reactor and second reactor; 
 a pentasil-based zeolite catalyst; 
 the reactors configured whereby each reactor has different conditions of conversion of hydrocarbons to aromatics; 
 a separation unit connected to receive an output mixture from the second reactor, whereby the separation unit separates the output mixture into a liquid fraction and gaseous fraction, and wherein the separation unit comprises a liquid fraction output and a gaseous fraction output; 
 a line connecting the gaseous fraction output to the first and second reactors; 
 the separation unit comprising a module for separating the gaseous fraction into hydrogen-containing gas and the natural gas liquids containing olefins, and wherein the separation unit comprises a hydrogen-containing gas output; 
 a line connecting the hydrogen-containing output to an oxygenate synthesis unit to the first reactor, the second reactor or both the first and the second reactors; wherein the installation comprises a liquid hydrocarbon and water condenser installed after the first reactor and before the second reactor and a separator for separating the liquid fraction. 
 
     
     
       4. An installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons, the installation comprising:
 a serially connected first reactor and second reactor; 
 a pentasil-based zeolite catalyst; 
 the reactors configured whereby each reactor has different conditions of conversion of hydrocarbons to aromatics; 
 a separation unit connected to receive an output mixture from the second reactor, whereby the separation unit separates the output mixture into a liquid fraction and gaseous fraction, and wherein the separation unit comprises a liquid fraction output and a gaseous fraction output; 
 a line connecting the gaseous fraction output to the first and second reactors; 
 the separation unit comprising a module for separating the gaseous fraction into hydrogen-containing gas and the natural gas liquids containing olefins, and wherein the separation unit comprises a hydrogen-containing gas output; 
 a line connecting the hydrogen-containing output to an oxygenate synthesis unit to the first reactor, the second reactor or both the first and the second reactors; wherein the installation comprises a liquid hydrocarbon and water condenser installed after the second reactor, serially connected to a three-phase conversion product separator into reaction water, liquid hydrocarbons, and discharge gases. 
 
     
     
       5. An installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons, the installation comprising:
 a serially connected first reactor and second reactor; 
 a pentasil-based zeolite catalyst; 
 the reactors configured whereby each reactor has different conditions of conversion of hydrocarbons to aromatics; 
 a separation unit connected to receive an output mixture from the second reactor, whereby the separation unit separates the output mixture into a liquid fraction and gaseous fraction, and wherein the separation unit comprises a liquid fraction output and a gaseous fraction output; 
 a line connecting the gaseous fraction output to the first and second reactors; 
 the separation unit comprising a module for separating the gaseous fraction into hydrogen-containing gas and the natural gas liquids containing olefins, and wherein the separation unit comprises a hydrogen-containing gas output; 
 a line connecting the hydrogen-containing output to an oxygenate synthesis unit to the first reactor, the second reactor or both the first and the second reactors; wherein the installation comprises a module for stripping discharge gas to recover the natural gas liquids containing olefins installed after the three-phase separator and a module for stabilizing hydrocarbon condensate to remove the natural gas liquids from the condensate. 
 
     
     
       6. An installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons, the installation comprising:
 a serially connected first reactor and second reactor; 
 a pentasil-based zeolite catalyst; 
 the reactors configured whereby each reactor has different conditions of conversion of hydrocarbons to aromatics; 
 a separation unit connected to receive an output mixture from the second reactor, whereby the separation unit separates the output mixture into a liquid fraction and gaseous fraction, and wherein the separation unit comprises a liquid fraction output and a gaseous fraction output; 
 a line connecting the gaseous fraction output to the first and second reactors; 
 the separation unit comprising a module for separating the gaseous fraction into hydrogen-containing gas and the natural gas liquids containing olefins, and wherein the separation unit comprises a hydrogen-containing gas output; 
 a line connecting the hydrogen-containing output to an oxygenate synthesis unit to the first reactor, the second reactor or both the first and the second reactors; wherein the installation comprises a circulation compressor installed after the three-phase separator.